A) Field of the Invention
This invention relates to the field of mulch manufacturing generally. More particularly, this invention relates to the field of manufacturing a mulch product having particular gradation characteristics from a naturally insect and rot resistant wood. The resulting mulch product is made of generally a coarsely divided portion, a finely divided portion, and a stringy binding portion.
B) Description of the Prior Art
Mulch products are widely known and used in the landscaping industry. The mulch products which have been developed over the years can generally be divided according to the methods used in the manufacturing process and the resulting product.
With respect to methods of manufacturing, there exists at least three known methods of manufacturing for which machinery is generally available. The first of these methods is the fixed hammer (or punch and die) method for creating a divided wood product. This method consists of loading a mulch machine from either the top or side so as to pace wood product against a spinning hammer. The spinning hammer forces the loaded wood product against a screen by the series of fixed position rotating hammers. As the product is forced between the spinning hammer and screen and ultimately through the screen, the wood product naturally divides according to the size hole through which the product is passed. The hole sizes in the screens vary, but can be in the range of 1-2 inches.
This method results in a relatively uniform chip product having little or no pulverized portion. The reason behind the lack of pulverization lies in the fact that the hammers which are rotated against the loaded wood product are fixedly attached in a relatively unmoving position to a rotating shaft. The hammers are rotated a predetermined distance from a surrounding screen and loaded wood product is forced into the space between the rotating hammers and surrounding screen. As such, with each sweep of the hammers, loaded wood product is pushed through the screen and forced to divide into smaller pieces. The spinning fixed hammers rapidly make successive sweeps and pass chips out with each sweep.
This method of mulch manufacture requires a powerful rotational force for the fixed hammers to consistently force wood product between the hammers and screen. If the power source is insufficient, the rotating hammers will jam as wood product wedges between the screens and hammers. Also, the associated supporting equipment for the screens and the hammers must be fairly resistant to deformation, i.e., heavy gage metal. If the hammers and screens are able to displace one with respect to the other, the machine is subject to repeated jamming.
A second known method of manufacturing mulch is to use an apparatus similar to the apparatus used for the fixed hammer system, with the exception that the hammers are rotatably affixed to the rotating shaft, i.e., with each stroke the hammers swing outwardly from the mounting shaft. In this manner, as the hammer swings, centrifugal action displaces the hammer head towards the surrounding screen. In the event the hammer is unable to displace loaded wood through the screen during a particular stroke, the hammer rotates backwardly with respect to the rotation of the supporting shaft to clear the wood product and leave it in place against the screen. In this manner, a piece of wood product between the screen and hammers is successively pulverized by the swinging hammers until the product is sufficiently divided to pass through the surrounding screens.
Owing to the pulverization and splintering process which the wood product is subject to in the swinging hammer process, a much more divided and shattered mulch product is created. The holes in the surrounding screens through which pulverized wood product pass has been in the range of 1-2 inches in prior art swinging hammer mulch machines. The resulting prior art mulch product is regularly sized and is finely divided into filaments of varying length.
A third method of creating a mulch product is by chipping. This method is commonly used for tree and shrub trimming disposal wherein a length of wood product is fed directly against a rapidly spinning chipping wheel. The spinning wheel simultaneously draws the length of wood onto the grinding surface and shears wood chips off the wood. A uniformly sized and generally non-pulverized mulch product is formed.
The foregoing products exhibit problems when used for mulching purposes. Since a mulch product is intended to provide ground cover between shrubs and other garden plants to retain moisture and smother weeds, it is helpful if the mulch stays in place after application, i.e., is resistant to being carried off by rain, strong wind, and other environmental effects. The first and thirdly described mulch products of uniformly sized and graded product is particularly susceptible to being removed. The larger sized particle chips simply float away. Owing to the fact that wood is generally less dense than water, particularly after the wood has been divided, the regularly sized chipped wood product is well suited to be lifted by flowing water currents and being carried until the water loses the necessary energy to move the mulch. Needless-to-say, mulch is not useful when it is carried to positions other than intended, and can further cause clogging of drainage ways, grates, etc. throughout the garden.
Similarly, when rain strikes the secondly described finely divided wood product (made by the swinging hammer method), the force of the falling water can displace the filaments away from their original position simply by the force of impact of the water against the distributed mulch. Although the finely divided product will eventually absorb enough water to stay in place, the time required for this to occur is too long for such methods to be effective against a 30-40 minute rain storm. As such, the product is washed away just as is the chip product.
In view of the foregoing problems associated with known mulch products, the present invention is directed to a method and resultant mulch product which is not easily removed by exposure to ordinary environmental factors. Specifically, the present product is a mulch including a finely divided portion, a course portion, and a stringy binding portion. This unique blend of sizing of shredded, splintered, shattered, and divided wood product is created by a novel mulch production method.